Chimerism Testing and Engraftment Monitoring

Tests

• Informatives (recipient & donor)
• Whole Blood / Bone Marrow
• CD3 cell subset – T Cells
• CD14/15 cell subset - Monocytes
• CD19 cell subset – B Cells
• CD33 cell subset – Myeloid cells
• CD34 cell subset – Hematopoietic stem and progenitor cells
• CD56 cell subset – NK cells
• CD71 cell subset – Reticulocytes, erythroid progenitors, activated T and B lymphocytes, macrophages, and all proliferating cells
• Granulocyte cell subset 

Purpose

• To monitor engraftment after allogeneic hematopoietic stem cell transplant (HCT).
• To detect relapse after allogeneic HCT.
• To determine maternal engraftment.
• To test genetic identity: STR testing can distinguish between monozygotic and dizygotic twins.
• To detect sample exchanges.

Highlights  

• Chimerism testing is performed by analyzing short tandem repeats (STR) using an in-house developed and optimized test. The test measures the relative quantities of STR allele products between the donor and recipient. A panel of thirteen STR loci are targeted for this test. The size of each STR allele is determined for donor and recipient at pre-transplant to identify loci that are unique (i.e., informative signatures to distinguish donor and recipient). Two informative loci are selected for subsequent testing. Each specimen is tested in duplicate at each locus. A standard curve containing different mixtures of pre-transplant recipient and donor DNA is included. The standard curve includes the following mixtures: 0%, 1%, 5%, 10%, 25%, 50%, 75%, 90%, 95%, 99%, and 100% donor DNA. These mixtures are used to determine the level of sensitivity for detecting minor cell populations.
• Achieves a sensitivity of 1%, higher compared to commercially available testing methods because ITL’s chimerism testing does not involve multiplexing.
• Cell subsets are prepared using Ficoll gradient and magnetic particles. The purity of each subsets is determined by flow cytometery. The subset purity is usually >90%. The percent purity of each cell subset is reported in the test report.
• ITL performs chimerism analysis on whole blood, whole marrow, core cell subsets (T cells, B cells, and monocytes from blood and CD34 progenitor cells from marrow), and supplemental cell subsets (CD33, CD56, and CD71).
• Donor chimerism is reported as % donor. In addition to the current sample-specific test results, chimerism report includes historical data performed for the specific transplant. In addition, the report includes graphs (separate graphs for peripheral blood and bone marrow) showing percent of donor chimerism for subsets over post-transplant sample collection points. 
• Consultation is available for test selection and interpretation of results.

• Routine testing reported in 3-10 business days*
• STAT testing reported in ≤ 3 business days*

* Additional 2-5 days if informative loci required